Did you change the game code? There is somewhere in the memcard file where its written the sl*s code of the game. It should be written over the disk, and in the box fo the game. It must be also one of the files on the CD, and should look like sles-02084 or something like that, maybe other numbers, or the sl*s part slightly different. Find that in your game, then in the memcard, and overwrite in the memcard. Try if it helps.
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